Electric circuit breaker



Aug. 14, 1934.

w. E. PAUL. 1,97%392 ELECTRIC CIRCUIT BREAKER Filed Jun 15, 1931lnvantov z William Elpaaul, y

H i5 Attmrney.

Patented Aug. 14, 1934 UNITED STATES PATENT OFFICE General ElectricCompany,

York

Application June 15, 1931,

6 Claims.

My invention relates to electric circuit breakers, more particularly tocircuit breaker tripping mechanism for effecting circuit openingmovement at high speed immediately in response to the tripping impulse.

In the operation of modern high tension transmission systems comprisinga network of high tension lines interconnecting a number of generatingstations, it is often necessary to clear a circuit upon the occurrenceof a short circuit or other fault within a few cycles in order tomaintain system stability. The conventional oil circuit breakersgenerally used for this purpose receive a tripping impulse through atrip coil, the trip coil in turn actuating a latch or release causingswitch opening movement. Since the movin parts of the breaker, includingthe usual linkage mechanism, operating rod and bridging member, are ofconsiderable mass, acceleration of the movable structure involves acertain time lag after the release. This, together with the timerequired for the coil to release the mechanism, comprises the timebetween the tripping impulse and the separation of the switch contactsand may take up a number of cycles endangering system stability unlessthe circuit is interrupted within a cycle or so of arcing.

It is a principal object of my invention to provide an improved highspeed circuit breaker wherein the tripping mechanism acts directly on amovable switch member of comparatively small massfor opening the circuitimmediately in response to the tripping impulse.

In accordance with my invention the movable switch member of the circuitbreaker is operatively related to an operating rod through a connectionallowing relative movement between the same, the said switch membercomprising the current-carrying element of electromagnetic trippingmeans for releasing said switch member with respect to said rod Forinsuring rapid opening movement of the switch member independently ofthe operating rod immediately upon actuation of the electromagnetictripping means energy storing means, as compression springs, areprovided. By reason of the small mass of the switch member as comparedwith the operating rodand associated mechanism acceleration of thesameby the energy storing means is very rapid.

My invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out withparticularity in, theclaims annexed to and forming a part of this specification,

a corporation of New Serial No. 544,306

Referring to the drawing, Fig. 1 illustrates an elevational view, partlyin section, of the contact structure of a circuit breaker embodying myinvention, and Fig. 2 is a sectional detailed view of the trippingmechanism.

As illustrated in the drawing my invention is shown applied to a fluidbreak or oil circuit breaker of a well-known type wherein a pair ofcontact structures immersed in oil are interconnected by a conductingbridging member to complete the circuit. It shall be understood,however, that my invention is readily applicable to circuit breakers ofother types wherein immediate and high speed opening movement isdesired.

The circuit breaker in the present instance comprises a movable switchmember, as the bridging member 1 formed of spaced conducting bars,relatively movable with respect to the operating or lift rod 2, andinterconnecting a pair of stationary contact structures, as explosionchamber pots 3 and 4 of a well-known type. The explosion chamber potsare supported at the lower ends of the insulating bushings 5 and 6 whichare mounted in the cover of the circuit breaker tank (not shown) andthrough which the lead-in conductors '7 and 8 extend. In the closedcircuit position illustrated in Fig. 1 the circuit between the lead-inconductors I and 8 is established by the bridging member 1 and attachedrod contacts 9 and 10 which extend within the explosion chambers andengage the corresponding stationary contacts which are electricallyconnected to the corresponding lead-in conductors. In the conventionalcircuit breaker of this type the operating rod 2 is rigidly connected tothe bridging member 1, and the tripping mechanism is associatedwithlevers and toggle links operatively connected to the rod 2 so that whenthe tripping impulse occurs the mass of the entire structure must beaccelerated in effecting separation of the switch contacts.

For the purpose of permitting switch opening movement of the bridgingmember 1 independent- 1y of the operating rod 2 there is providedtripping mechanism comprising the latches ll pivotally mounted as at 12between a pair of plates 13 suitably secured to the operating rod 2. Theplates 13 are spaced as illustrated in Fig. 2 and form guiding meanswithin which the bridging member 1 may move vertically between upper andlower limits. The bridging member is held in the upper closed circuitposition illustrated against the bias of compression springs 14 by thelatches 11 so that the bridging member and rod are locked together as aunit. The springs 14 seat at one end on the stationary lugs 15 securedto the rod 2 and at the opposite end on a pair of members 16 secured asat 17 to the bridging member 1. Each member 16 is provided with a lug 18coacting with a roller 19 carried by one arm of the corresponding latch11, each latch being biased in a clockwise or latching position as by aspring 20. With the bridging member 1 latched in position asillustrated, the springs 14 are under compression and upon release ofthe members 16 by the latches 11 the bridging memher 1 is Immediatelyurged in a downward or circuit opening direction independently of therod 2.

The tripping impulse inthe present instance, causing actuation ofthelatches 1,1, is derived from a pair of U-shaped electromagnets 21which are secured to the plates 13 and straddle the bridging member 1 soas to be energized bycur-- rent flowing through the switch. Opposite theupper open end of each magnet 21 is a bar shaped armature 22 forming anextension of latch 11. Accordingly, energization of theelectromag: nets21 by current through the bridging member suificient to attractl thecoacting armature 22 serves to trip the breaker and cause openingmovement gof the bridging member 1 by the compression springs l4. Theconnection allowing relative movement betweenthe rod 2 and bridging,member 1 is preferably so designed that the circuit, is normallycleared by the travel of the bridgingmember alone. g

,It .will therefore benoted that only theessentiaLcuIIent-carrying partsof the switch move during the circuit interrupting. operation, it beingunderstood of course that the operating rod 2 maydllgewise be operatedin the usual manner to increasethe distanceof'separation between thecontacts. Such an arrangement is moreover preferred since the energystored in the moving opcrating. rod may be used to reset the latchingmechanism so that theswitch is in readiness for a subsequent closingoperation. To this end there arel rovidedla pair of buffers 23, eachcomprising a; compressionspring 24 and acap 25 slidable on asstop member26, the buffers being disposed on astationary part of the circuitbreaker substantially below the opposite ends of the bridging member 1;In,the dotted line position of'the movable contact structure thebridging member 1 has moyed to its lower limit with respect to theoperating rod; 2 WhiCh has now likewise descendedWWhen the bridgingmember 1 strikes the buiiers 23 it is stopped without: shock whereas theinertia. ofthe operating rod 2 causes it to continue its downwardmovement with the result that the springs 14 are again compressed andthe latches 11 are cammed over the corresponding lugs 18 and snap intothe latching position as shpwnin the full linefigure. The circuitbreaker is,th ereore immediately in readiness fora reclosing operationand in case the short circuit or other fault; still persists the breakeris again imm diatelytripped free of the operating rod.

which the breaker "is trippedi It should be understood that my inventionis not limited to specific details of construction and arrangementthereof herein illustrated, and that changes and modifications may occurto one skilled in the art without departing from the spirit of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electric circuit breaker comprising a pair of stationary contactstructures and a movable conducting bridging member connecting saidstructures in the closed circuit position, an operating rod relativelymovable with respect to said bridging member, springs biasing saidbridging member towards open circuit position independently of said rod,and electromagnetic tripping means including said bridging member and alatch pivotally mounted member at high speed. l

2. In an electric circuit breaker comprising relativelymovablecontactsincluding a conductto member.

member, a latch locking said bridging member to said rod as a unit, aspring biasing said bridging member towards open circuit positionindependently of said rod in response to actuation of said latch, andmeans limiting the circuit opening movement of said bridging member sothat the inertia of said operating rod is efiective to cause resettingof said latch.

6. Circuit interrupting apparatus comprising stationary contactstructure and a movable bridging member coacting therewith, an operatingrod relatively movable with respect to said bridging member and formingguiding means therefor, a latch locking said bridging member to said rodas a unit, a spring biasing said bridging member towards open circuitposition in response to release of said latch, electromagnetic meansenergized by current through said bridging member for actuating saidlatch and causing opening movement of said bridging member, the travelof said bridging member with respect to said rod being sufiicientnormally to clear the circuit, and means other than said rod limitingthe opening movement of said bridging member causing resetting of saidlatch and compression of said spring by the inertia of said rod.

WILLIAM E. PAUL.

